Support Set Operators for SELECT Stmts

Author: JoshInnis

regress/expected/new_cypher.out

@@ -184,6 +184,27 @@ SELECT sum(salary) OVER w, avg(salary) OVER w
 ERROR:  syntax error at or near "("
 LINE 1: SELECT sum(salary) OVER w, avg(salary) OVER w
                   ^
+SELECT a.i FROM tst a
+UNION
+SELECT a.i FROM tst a;
+ i 
+---
+(0 rows)
+
+SELECT a.i FROM tst a
+EXCEPT
+SELECT a.i FROM tst a;
+ i 
+---
+(0 rows)
+
+SELECT a.i FROM tst a
+INTERSECT
+SELECT a.i FROM tst a;
+ i 
+---
+(0 rows)
+
 DROP GRAPH new_cypher CASCADE;
 NOTICE:  drop cascades to 2 other objects
 DETAIL:  drop cascades to table new_cypher._ag_label_vertex

regress/sql/new_cypher.sql

@@ -92,5 +92,17 @@ SELECT sum(salary) OVER w, avg(salary) OVER w
   FROM empsalary
   WINDOW w AS (PARTITION BY i ORDER BY i DESC);
 
+SELECT a.i FROM tst a
+UNION
+SELECT a.i FROM tst a;
+
+SELECT a.i FROM tst a
+EXCEPT
+SELECT a.i FROM tst a;
+
+SELECT a.i FROM tst a
+INTERSECT
+SELECT a.i FROM tst a;
+
 DROP GRAPH new_cypher CASCADE;
 DROP GRAPH new_cypher_2 CASCADE;

src/backend/parser/cypher_gram.y

@@ -82,6 +82,7 @@ typedef struct GroupClause
 	List   *list;
 } GroupClause;
 
+static Node *makeSetOp(SetOperation op, bool all, Node *larg, Node *rarg);
 static void insertSelectOptions(SelectStmt *stmt,
 								List *sortClause, List *lockingClause,
 								SelectLimit *limitClause,
@@ -615,7 +616,7 @@ simple_select:
 					n->targetList = list_make1(rt);
 					n->fromClause = list_make1($2);
 					$$ = (Node *)n;
-				}
+				}*/
 			| select_clause UNION set_quantifier select_clause
 				{
 					$$ = makeSetOp(SETOP_UNION, $3 == SET_QUANTIFIER_ALL, $1, $4);
@@ -627,7 +628,7 @@ simple_select:
 			| select_clause EXCEPT set_quantifier select_clause
 				{
 					$$ = makeSetOp(SETOP_EXCEPT, $3 == SET_QUANTIFIER_ALL, $1, $4);
-				}*/
+				}
 		;
 
 
@@ -4696,3 +4697,15 @@ insertSelectOptions(SelectStmt *stmt,
 		stmt->withClause = withClause;
 	}
 }
+
+static Node *
+makeSetOp(SetOperation op, bool all, Node *larg, Node *rarg)
+{
+	SelectStmt *n = makeNode(SelectStmt);
+
+	n->op = op;
+	n->all = all;
+	n->larg = (SelectStmt *) larg;
+	n->rarg = (SelectStmt *) rarg;
+	return (Node *) n;
+}